A person you dread seeing in a bar because you know when they see you, they will make a bee line straight for you, bore you with stories and questions and never get the hint to leave.
They are usually alone and drunk.

I was out last night in a bar when that MAYGRUM, John Smith came up to me again and told me that same stupid story about how he knew me when i was a kid. He followed us to the next bar but we eventually lost him in the nightclub.